From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mike Galbraith <efault@gmx.de>
Cc: tglx@linutronix.de, linux-rt-users@vger.kernel.org,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RT] 5.9-rt14 softirq_ctrl.lock vs listening_hash[i].lock lockdep splat
Date: Mon, 12 Oct 2020 18:45:53 +0200 [thread overview]
Message-ID: <20201012164553.kkk7aaeyb3y4wvyh@linutronix.de> (raw)
In-Reply-To: <12d6f9879a97cd56c09fb53dee343cbb14f7f1f7.camel@gmx.de>
On 2020-10-10 06:31:57 [+0200], Mike Galbraith wrote:
so this then. Do you have more of these?
----------->8--------------------
Subject: [PATCH] tcp: Remove superfluous BH-disable around listening_hash
Commit
9652dc2eb9e40 ("tcp: relax listening_hash operations")
removed the need to disable bottom half while acquiring
listening_hash.lock. There are still two callers left which disable
bottom half before the lock is acquired.
Drop local_bh_disable() around __inet_hash() which acquires
listening_hash->lock, invoke inet_ehash_nolisten() with disabled BH.
inet_unhash() conditionally acquires listening_hash->lock.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
net/ipv4/inet_hashtables.c | 19 ++++++++++++-------
net/ipv6/inet6_hashtables.c | 5 +----
2 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 239e54474b653..fcb105cbb5465 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -585,7 +585,9 @@ int __inet_hash(struct sock *sk, struct sock *osk)
int err = 0;
if (sk->sk_state != TCP_LISTEN) {
+ local_bh_disable();
inet_ehash_nolisten(sk, osk);
+ local_bh_enable();
return 0;
}
WARN_ON(!sk_unhashed(sk));
@@ -617,11 +619,8 @@ int inet_hash(struct sock *sk)
{
int err = 0;
- if (sk->sk_state != TCP_CLOSE) {
- local_bh_disable();
+ if (sk->sk_state != TCP_CLOSE)
err = __inet_hash(sk, NULL);
- local_bh_enable();
- }
return err;
}
@@ -632,17 +631,20 @@ void inet_unhash(struct sock *sk)
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct inet_listen_hashbucket *ilb = NULL;
spinlock_t *lock;
+ bool state_listen;
if (sk_unhashed(sk))
return;
if (sk->sk_state == TCP_LISTEN) {
+ state_listen = true;
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
- lock = &ilb->lock;
+ spin_lock(&ilb->lock);
} else {
+ state_listen = false;
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+ spin_lock_bh(lock);
}
- spin_lock_bh(lock);
if (sk_unhashed(sk))
goto unlock;
@@ -655,7 +657,10 @@ void inet_unhash(struct sock *sk)
__sk_nulls_del_node_init_rcu(sk);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
unlock:
- spin_unlock_bh(lock);
+ if (state_listen)
+ spin_unlock(&ilb->lock);
+ else
+ spin_unlock_bh(lock);
}
EXPORT_SYMBOL_GPL(inet_unhash);
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 2d3add9e61162..50fd17cbf3ec7 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -335,11 +335,8 @@ int inet6_hash(struct sock *sk)
{
int err = 0;
- if (sk->sk_state != TCP_CLOSE) {
- local_bh_disable();
+ if (sk->sk_state != TCP_CLOSE)
err = __inet_hash(sk, NULL);
- local_bh_enable();
- }
return err;
}
--
2.28.0
next prev parent reply other threads:[~2020-10-12 16:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-10 4:31 [RT] 5.9-rt14 softirq_ctrl.lock vs listening_hash[i].lock lockdep splat Mike Galbraith
2020-10-12 16:45 ` Sebastian Andrzej Siewior [this message]
2020-10-12 18:34 ` Mike Galbraith
2020-10-13 3:00 ` Mike Galbraith
2020-10-14 10:22 ` Sebastian Andrzej Siewior
2020-12-09 10:05 ` Peter Zijlstra
2020-12-09 10:25 ` Mike Galbraith
2020-12-09 10:32 ` Sebastian Andrzej Siewior
2020-12-09 11:47 ` Sebastian Andrzej Siewior
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